1. Field of the Invention
The invention is directed to a curved reflective surface capable of providing a substantially undistorted wide-angle field of view and a computer program for forming said reflective surface. The invention may have applications in the field of illumination optics and driver's side mirrors.
2. Description of the Related Technology
The U.S. Department of Transportation reported that lane changes and merger (LCM) crashes alone accounted for approximately 244,000 crashes in the United States in 1994, causing 225 deaths and many serious injuries. This figure represents approximately 4% of all vehicular crashes and is largely attributed to the minimal view provided by side view mirror's. For most passenger side mirrors, the optical axis of the viewer's eye reflects off the mirror at approximately a 90° angle. A flat driver side view mirror, however, typically provides a viewing angle of approximately 15°. Therefore, to ensure driver safety, there is a need to develop wide-angle side view mirrors, particularly wide-angle driver's side view mirrors, capable of enlarging the reflected field of view when the mirror is viewed from the typical driver's position.
It is known to use curved mirrors to enlarge a field of view. For example, curved mirrors have previously been incorporated in the rear view and side view mirrors of automobiles, as disclosed in U.S. patent publication nos. 2003/0039039, 2003/0081334 and 2004/0114260 and U.S. Pat. Nos. 6,979,090, 6,069,755, 5,980,050, 5,166,833, 4,580,881 and 4,331,382.
Other forms of curved mirrors include side view mirrors that are capable of being manipulated into a curved configuration, such as is disclosed in Korean patent publication KR 1004847. The reflected images of these mirrors, however, are generally significantly distorted, depending upon the curvature and shape of the mirror.
Distorted images are non-perspective projections. A perspective projection, by contrast, is formed by tracing a line from the image plane through a point, known as the focal point or center of projection, until it touches an object in the scene. Pinhole cameras, for example, utilize this method for forming perspective images.
Historically, it was only possible to construct mirrors in spherical or parabolic shapes for traditional applications, such as in telescope designs. In recent years though, it has become possible, through computer controlled machining, to create parts of almost any given mathematical shape. Consequently, it is now possible to make mirrors with an exactly prescribed geometry, even if it is highly irregular in shape. Although the technology exists for customizing the geometry of a reflective surface, as far as the applicant is aware, there currently exists no reflective surface capable of enlarging the field of view of a driver side view mirror and reflecting a substantially undistorted image.